Preheat the oven to 350°F (175°C) and lightly spray a 12-cup muffin pan with cooking spray.
Cook the spaghetti according to package directions until al dente, then drain well in a colander.
In a large bowl, toss the hot drained spaghetti with the melted butter, then mix in the whisked eggs and 1/2 cup grated Parmesan until the pasta is evenly coated.
Divide the coated spaghetti evenly among the 12 muffin cups and press the pasta down to form nests with a slight well in the center of each cup.
While the pasta cooks, brown the ground beef or turkey in a 10-inch skillet over medium heat, breaking it up as it cooks; drain excess fat.
Stir the taco seasoning, the can of diced tomatoes and green chiles (undrained), and 1/4 cup water into the browned meat; simmer 5 minutes, then remove from heat and stir in the 2 cups spaghetti sauce. Set aside.
In a small bowl, combine the cottage cheese, the remaining 1/4 cup Parmesan, and dried parsley; divide this cheese mixture among the pasta nests, spreading it into the wells.
Spoon the meat and sauce mixture over each cottage-cheese–lined spaghetti nest (you may have leftover sauce) and top each with shredded cheddar or Mexican blend cheese.
Bake for 30 minutes, until the cheese is lightly browned and the pies are heated through. Let cool a few minutes, then remove from the pan and serve with any leftover sauce if desired.